1. Field of the Invention
The invention herein relates to the decomposition of waste oil. More particularly it relates to oil decomposition using natural materials.
2. Description of the Prior Art
It has been known that dealginated, partially dewatered kelp residue (which for brevity herein may be referred to as xe2x80x9ckelp wastexe2x80x9d) is capable of absorbing various petroleum products. In 1991 applicant and colleagues obtained U.S. Pat. No. 5,009,790 for a method of cleaning up oil spills in the ocean or other body of water, such as would come from a leaking or wrecked oil tanker, using kelp waste as an absorbent. That patent disclosed that a variety of different petroleum products could be absorbed by the kelp waste. In that patent it was also taught to collect the oil-saturated kelp waste after absorption and then recover the oil by placing the oil-saturated kelp waste in a cracking furnace and thermally cracking the absorbed oil. The cracked oil products could then be recovered, and the kelp waste would be burned away at the cracking temperatures.
The system contemplated and disclosed in that patent therefore was directed to cleanup of an oil spill and recovery of the valuable spilled oil.
It has also been known that certain bacteria have the ability to xe2x80x9ceatxe2x80x9d oil, in that they act on oil products to convert the oil from hydrocarbon compounds to simpler compounds such as water and carbon dioxide. All such prior processes using such bacteria have required that the bacteria be separately obtained and placed in contact with the oil. Such was tried several times, for instance, by depositing quantities of bacteria on oil spills. Such trials were generally failures, in that the nature of many spilled oil products and the environmental conditions under which they are found were incompatible with bacteria decomposition.
An entirely different problem with oil products also exists, which is the problem of disposal of oil products in small quantities, which do not lend themselves to either easy recovery or easy disposal. In most cases such small quantities of oil products, such as motor oil drained from a vehicle engine, must be collected and accumulated into large volumes which can then be disposed of by burning. Alternatively, in some cases the collected oil is in sufficient quantities to permit its use economically as a reactant to form other products, or to be filtered or fractionated for reuse as a lubricant. In all of these cases, it is necessary to collect large quantities of such oil products and transport them, often over long distances, to the site where the products can be burned, reacted or recovered. This type of operation is usually hampered by the fact that many of the products contain additives or contaminants, such as metals, which must be removed before the oil can be burned, reacted or recovered.
I have now discovered that, because kelp waste contains bacteria which can break down oil products, placing such oil products in contact with the kelp waste and maintaining that contact for a period of time under conditions favorable to bacterial action, will result in decomposition of the oil products by the bacteria into by-products such as methane, water and carbon dioxide. In using this process, there is no need for high temperatures such as required for oil cracking. Further, since the appropriate conditions for bacterial activity occur directly as part of this process, there is no need for elaborate procedures to maintain bacterial activity. The process of the invention results in decomposition of the oil, not merely absorption of it, so that no further disposal is needed. The kelp waste can itself be readily disposed of after use, since it can be safely burned, incorporated into landfill or even used as mulch or organic builder in soil.
This process can be implemented for any quantity of oil disposal, but it is best suited for disposing of relatively small quantities of oil, such as could be collected by a person who personally changes the oil in his or her car, or by a small vehicle repair shop or facility, or on a family farm, or the like. To this end this invention also contemplates a small disposal device which I refer to as a xe2x80x9cdigester.xe2x80x9d The kelp waste can be placed in this digester, which has a decomposition chamber which is usually closed but ventilated, so that the aerobic bacteria can be sustained, and the oil to be decomposed is added to the digester chamber. Ambient conditions are maintained at temperatures generally in the range of about 50xc2x0-80xc2x0 F. (10xc2x0-27xc2x0 C.), under which the bacteria thrive, for a time sufficient for the bacteria to decompose the oil. Small amounts of water are added periodically to maintain the bacteria, and the digester can be replenished simply by adding more kelp waste.